The present invention relates to a method and apparatus for crimping a multifilament yarn in a stuffer box.
German PS 26 32 082 and U.S. Patent Nos. 3,373,470; 3,482,294; and 4,724,588 all disclose an apparatus for the continuous stuffer box crimping of a thermoplastic yarn, and wherein a heated treatment fluid advances the yarn by means of an injector into a stuffer box having a side wall which is permeable to the fluid. The yarn forms a closely packed filamentary body or plug in the stuffer box, and the yarn is drawn off from the stuffer box and wound into a package.
During the stuffer box crimping of multifilament yarns, it is among other things, an object to mingle the filaments of the individual yarns in such a manner that the individual filaments no longer appear in the finished yarn product. Attempts have been made to achieve this object by a particularly intensive stuffer box crimping, which is accomplished primarily by increasing the stuffer box pressure. In the case of pneumatic stuffer boxes this occurs in particular by the adjustment of the pressure and/or the temperature of the heating gas, heating air, or heating vapor, which is applied to the yarn and serves to advance the yarn into the crimping portion of the stuffer box.
In accordance with the present invention, it has been found that the intensification of the crimping in a pneumatic stuffer box can also be varied irrespective of the parameters of the pneumatic conveying component, and this is an object of the present invention.